Greywater is household wastewater from laundry tubs, washing machines, showers, baths and basins. Kitchen sinks and dishwashers are included under the term “greywater” but tend to contain higher levels of contaminants than other greywater sources. Changing domestic lifestyles are driving an increase in water use, creating a need for sustainable options for reuse or disposal of the resulting wastewater.

Many regional and district councils are now considering alternative water management strategies, including rainwater collection and greywater diversion. However, no national legislation or guidelines currently exist for rainwater or greywater practices, and there is a lack of health risk assessment data specific to New Zealand conditions. Given the prevalence of unreported greywater re-use, the CIBR's greywater experts believe research needs to be conducted to address this.